Microsoft: 64-Bit Office 2010 Not Ready

Are you thinking about deploying the 64-bit version of Office 2010? If so, Microsoft wants you to think again.

Microsoft's newest productivity suite, slated for public release as early as May 12, will be available in both 32-bit and 64-bit versions -- a first for the Office product line. The advantage of tapping into 64-bit metal includes the ability to handle files that require greater memory support, as well as to run more programs concurrently.

However, Microsoft explained late last month that its 64-bit Office 2010 isn't really ready for prime time after all.

More specifically, the add-ins, controls and Visual Basic for Applications (VBA) programming code that need to be compatible with 64-bit Office 2010 still need to be updated, Microsoft explained in a blog. Consequently, Microsoft is recommending that Office 2010 users install the 32-bit version of the program, even when using a 64-bit Windows operating system with the productivity suite.

The 32-bit and 64-bit versions of Office 2010 are "largely indistinguishable" except for memory capacity, according to Ted Way, a Microsoft program manager for product lifecycle and engineering excellence.

"The extra memory capacity comes at the cost of some compatibility with existing extensions to Office, such as 32-bit versions of ActiveX Controls and some third-party add-ins, in addition to 32-bit versions of programs that interface directly with Office," Way wrote in the blog. "New versions of these extensions will need to be obtained, and it will take some time for 64-bit compatible extensions to be made available."

Way explained that 32-bit Office 2010 can handle files that soak up about 4GB of memory. When the 64-bit version is ready, Office 2010 will be able to access about 17 billion GB of memory, he added.

Eventually, Microsoft expects the 64-bit version of Office to be widely used. For now, the install program (setup.exe) defaults to the 32-bit version, which will run on a 64-bit operating system. Users who really want to run the 64-bit version can do so by opening a folder on the CD-ROM containing the executable install file.

Trying to run both the 32-bit and 64-bit versions of Office 2010 on the same machine is not supported, Way said. In addition, the install program will block the installation of the 64-bit version if it finds certain 32-bit Office apps already installed, such as Outlook. However, some 32-bit products are on Microsoft's "allowed list," permitting the installation of Office 2010 64-bit to proceed. Allowed-list products include Expression Web Designer, Microsoft Office Web components and the VBA 6.4 software development kit, Way said.

VBA will work with the 64-bit version of Office 2010, but developers need to do a little tweaking of the external interfaces, according to Danny Khen of Microsoft, commenting in the blog. Developers will have to update the Declare statements of VBA code that has "handles/pointers as arguments," Khen explained. Microsoft released a tool called the "Microsoft Office 2010 Code Compatibility Inspector" to help automate the update process, as described in this blog. There also are some free tools to help with migration to Office 2010.

Microsoft plans to release a new version of VBA, version 7, with the release of the 64-bit version of Office 2010, according to a Microsoft white paper. VBA 7 will work with both the 32-bit and 64-bit version of Office 2010. However, developers using the 64-bit version of Office 2010 still must update the APIs to get the VBA 7 code to work, or use the Code Compatibility Inspector tool to fix those APIs.